That could mean the tens of thousands of vehicles that cross the bridge daily may spend less time at a standstill waiting for it to open and close, which on average lasts about five minutes.

Last year, the Fremont Bridge opened more than 5,500 times.

Traffic Lab is a Seattle Times project that digs into the region’s thorny transportation issues, spotlights promising approaches to easing gridlock, and helps readers find the best ways to get around. It is funded with the help of community sponsors Alaska Airlines, CenturyLink, Kemper Development Co., NHL Seattle, PEMCO Mutual Insurance Company and Seattle Children’s hospital. Seattle Times editors and reporters operate independently of our funders and maintain editorial control over Traffic Lab content.

Right now, they stay down from 7 to 9 a.m. and from 4 to 6 p.m. weekdays. Large commercial vessels of more than 1,000 tons may request openings anytime.

In this week’s Traffic Lab Q&A, we took on that issue and answered another reader’s question about plans to extend Seattle’s South Lake Union streetcar line.

Here goes:

Q: Are officials considering expanding restrictions on when Seattle’s Ship Canal bridges open for noncommercial ships throughout the day? The constant bridge openings, sometimes to let just one sailboat through, considerably impact traffic — not just during weekday rush hour times when the current restrictions block the bridges from opening.

— Richard Simkins, Queen Anne

A: You might remember back in 2015 when the Seattle Department of Transportation (SDOT) said the current four-hour weekday restrictions — which have existed for decades — no longer reflect rush hours for the city’s booming population.

The department’s director, Scott Kubly, wanted more limits on openings for pleasure boats.

But SDOT now says it wants to try to improve traffic flow by making surface-street updates, such as installing new signal controls and sensors, before going to the Coast Guard.

Specifically, the department is planning upgrades on the north and south ends of the Fremont Bridge, the busiest bridge for openings, that aim to better coordinate timing of traffic signals with openings. Officials plan to add cameras, too, to keep a better eye on congestion in the area.

“With these coming investments, we believe it is prudent to evaluate operations once they are in place before proceeding with any request for a change in bridge operating restrictions,” the department said in a statement.

SDOT plans to complete the updates this summer, with the work totaling between $1.5 million and $1.8 million.

After raising the issue in 2015, SDOT collected feedback from a variety of groups, ranging from yacht clubs to neighborhood organizations. Roughly 500 people and organizations responded with emails and letters, most from motorists supporting more restrictions, the department said.

A daily average of about 28,800 vehicles crossed the Fremont Bridge in 2014, while nearly 60,000 traveled across the Ballard Bridge, according to the most recent numbers available.

To show how the openings affect them, the city says on its website that during the last week of August 2014, the Ballard Bridge opened 11 times between 6 and 7 p.m. on weekdays, while an average of 2,600 vehicles crossed during that same hour.

The streetcar hasn’t secured a $75 million grant project with the Federal Transit Administration. Local money would pay for the rest of the line’s price tag, currently budgeted at roughly $152 million, according to SDOT.

But because former President Barack Obama included the extension in his 2017 budget, SDOT transit director Andrew Glass Hastings said it isn’t “directly impacted” by Trump’s budget outline, which must go through many more steps before Congress approves a final spending plan.

How closely Congress will follow the president’s outline remains to be seen.

Money issues aside, the 1.2-mile extension would extend the tracks of the South Lake Union line south along Stewart Street and First Avenue to Pioneer Square, connecting with the First Hill line.

Project managers expect the line to carry 20,000 to 24,000 people through the busy area each weekday.

SDOT officials just this month approved an updated plan for the project that says construction would start in 2018 and the line would open in 2020.

Seattle Times reporter Mike Lindblom, who’s covered Seattle’s streetcar issues for years — most recently with a story about a March 1 incident in which a train slid 2½ blocks on First Hill — has more history on the city’s proposals:

Back in 2007, the City Council mapped out several other lines, including a north extension of the South Lake Union line up Eastlake Avenue East into the University District.

But officials scrapped that corridor and two others for the foreseeable future, he said, and Sound Transit’s light-rail line should reach the U District by 2021.

Got a question? Send it to trafficlab@seattletimes.com, and we may feature it an upcoming column.